Even food preferences seem to divide Senate Democrats and Republicans in an overnight vote-a-rama on a budget that will never take effect.

WASHINGTON — At times it seemed the overnight fight club in the U.S. Senate just wouldn't end.

For nearly 20 hours, senators considered more than 600 amendments, from lofty to less so, and voted on dozens. The marathon vote-a-rama did not end until just before dawn Saturday, when Democrats stumbled across the finish line and passed their first federal budget plan in four years.

In a final squeaker, the chamber voted 50 to 49 to approve a $3.7-trillion budget blueprint that would raise taxes on corporations and the wealthy, trim spending, invest new revenue to build infrastructure and tamp down the federal deficit.

Ordinarily, it would be an impressive achievement. But Republicans in the House had approved a sharply divergent budget days earlier that would slash taxes and spending, and radically shrink government. Reconciling the two plans is probably impossible, and neither will be put into effect.

Instead, the competing blueprints serve as partisan warning shots, establishing the outer edges of the battle for a broad deficit-reduction deal that President Obama and Republicans will start addressing after Congress returns on April 8 from a two-week recess.

No one expects a quick resolution. The GOP plan from Rep. Paul D. Ryan of Wisconsin, the party's 2012 vice presidential nominee, is far to the right of Obama's views. It would partially privatize Medicare, curtail spending on dozens of programs for the poor and reduce top tax rates for the wealthy. The Democratic version stakes positions to the president's left.

As exhausted lawmakers packed up to leave and Obama flew home on Air Force One from four days of diplomacy in the Middle East, the White House suggested a moment's reflection.

"Now it is time for our leaders to come together to find common ground," Press Secretary Jay Carney, who was traveling with Obama, said in a statement. "The president has put a plan on the table that reflects compromise, and he will continue to work with both sides to see if there is an opportunity to reach a solution to our budget challenges."

For now, the two sides can't even agree on menus. As the long night of legislating began, pizzas were delivered to some Democratic offices and barbecue was served on the Republican side.

Under Senate rules, the budget process allows unlimited amendments to be heard. It gives senators a once-a-year opportunity to bring priority topics to the floor in rapid fire, and just as quickly call for votes.

And for hour after hour they did just that.

The usually nearly empty chamber became a political mosh pit of colliding bills and bodies. Senators and their aides angled for attention, offering amendments in a head-spinning array that jumped from Wall Street reforms to domestic drone surveillance to the threatened sage grouse.

Not all got votes, but dozens did, and after four years without a budget, the pent-up desire to legislate was palpable. One senator, Tom Coburn (R-Okla.), had 66 amendments of his own.

There were measures to gut the nation's new healthcare law (failed) and to require White House officials to produce their own budget or risk not being paid (approved).

Even without becoming law, the value of the senators' votes in future campaign ads will be priceless.

And the tallies will be noted, in some cases, for future legislative ventures: A filibuster-proof 62 senators voted to support the proposed Keystone XL oil pipeline, giving a boost to a controversial project that has been stalled by the administration. The Senate unanimously opposed reducing Social Security cost-of-living adjustments, as Obama has considered.

As midnight neared, Senate Majority Leader Harry Reid (D-Nev.) calmly assessed the situation on the floor. "We are not at carnival stage yet," he said.

And so they carried on. Floor managers struggled to organize the mess, allotting each bill just minutes for debate. Senators, essentially held hostage, dared not miss their turns or votes.

Live tweeting slowed to a trickle as reporters and other onlookers tired out. Still the floor action stumbled on.

Democrats had not produced a budget for four years for several reasons. Earlier budget deals had already sealed spending levels, they reasoned. Besides, the Ryan budget had sparked intense criticism and they were happy to keep it aimed at the GOP.

Reid also was protecting his caucus from having to cast, for some, a tough vote. Indeed, four Democrats defected Saturday. All face reelection in conservative states.

But House Republicans had dared the Democrats not to act. They had slipped a provision into a bill that would suspend lawmakers' $174,000 annual salary if they failed to pass a budget.

At 4:38 a.m., the final vote was tallied. No Republicans voted yes.

"The only good news is that the fiscal path the Democrats laid out in their budget resolution won't become law," Senate Minority Leader Mitch McConnell (R-Ky.) said in a statement.

Cars were waiting to whisk senators away as they considered the next deadline, this summer, when Congress will need to raise the nation's debt ceiling or risk a credit default. It is an opportunity all sides see as a chance to strike a deal. Or at least spend a long night trying.